Endometriosis of the inguinal region: magnetic resonance imaging (MRI) findings.

A case of endometrioma of the right inguinal canal region, diagnosed preoperatively, is presented. The diagnosis was made on the basis of cyclical symptoms relating to menstrual periods, in combination with demonstration of blood products within an enhancing focal lesion in the inguinal region with magnetic resonance imaging. The case presented here is unique, as it is the first case, to our knowledge, of an endometriotic lesion in the inguinal canal to demonstrate the characteristic 'shading sign' at magnetic resonance imaging.